Using social networking sites like Facebook can make you eat too much. If that’s not bad enough, it can also make you spend too much, says a new study in the Journal of Consumer Research. The research, carried out by academics at Columbia University and the University of Pittsburgh, reveals that catching up with friends and socializing online can have a positive effect on self-esteem and well-being. This might sound like a good thing, but the study concludes that feeling good about yourself can actually have a detrimental impact on behavior by momentarily lowering one’s ability to say no. This naturally leads to over-indulgence whether it manifests itself in splurging on clothes you don’t need, or snacking on one, two or five too many holiday cookies.